Continuously fed centrifugal machine



y 19.59 H. M PHEE ET AL 2,893,562

CONTINUOUSLY FED CENTRIFUGAL MACHINE 2 Sheets-Sheet 2 Filed June 22. 1955 IN VEN TOR/f AL EXA NDEI? MMCPfi/EE C/MRLEI A. OLCOTT y THOMAJ REID FREDERICK JT/NDZ" W J W;

ATTORNEY for the syrup. A second stationary 2,893,562 CONTINUOUSLY FED CENTRIFUGAL MACHINE Alexander H. McPhee, Manhasset, N.Y., Charles A. 01-

cott, Hewitt, NJ., Thomas H. Reid, Brooklyn, N.Y., and Frederick Stindt, Cliifside Park, N.J., assignors to Hepworth Machine Company, Inc., Long Island City,

.N.Y.,. a corporation of .New York Application June 22, 1953, Serial No. 363,242 6 Claims. (01. 210-680) This invention relates to centrifugal machines and more particularly to improvements in sugar centrifugal mafed continuously thereto.

It is an object of this inventionto provide an improved continuously fed centrifugal machine which operates efficiently for both free-running and slow-running magmas.

Centrifugal machines of the continuous type have been proposed heretofore for the refining of sugar. In one such type, a perforated conical basket is provided and magma is continuously applied to the inside of the basket. The rotation of the basket results in centrifugal force which has the effect of causing the syrup or molasses to flow through the perforations in the side of the basket and causes the sugar to flow outward within the basket so that it can be discharged and kept separate from the liquid which has passed through the perforations. The holes in the basket are large enough to permit the escape of syrup but are small enough to retain the sugar in the basket.

The syrup escapesthrough theside of the basket into aconical skirt which is attached to and revolves with the basket. This, skirt is not'perforated so that the syrup flows into a first stationary housing where it is caught and discharged through a chute into a collecting canal housing is provided with a chute for collecting the sugar. There is a space betweenthe two stationary housings and this space is open to the atmosphere. It has been found that such a space is open tothe atmosphere. It'has been found that such a space is necessary because it is impossible to maintain the air pressure within the first housing always equal to that in the second housing. If there is a difference in pressure between these two housings and no space in between, there is an undesirable mixing of the sugar and syrup. Thus, if the air pressure in the second housing is higher thesecond housing into the first and into the syrup, which is of .course objectionable. Conversely, if'the air pressure in the first housing ishigher than that in the second housing, syrup flows from the first housing into the second and contaminates the dried sugar.

. Machines of the type just described have been built and operated but their efliciency in separating sugar from syrup has been so low as to preclude their general use in drying sugar even though a machine of this type has been used successfully for separating solids other than vsugar from a liquor.

One of the principal reasons why such a machine has .not been successful in drying sugar is that the characteristics of the sugar massecuites and magmas are subject to wide variation, particularly as to the facility with which the syrup leaves the sugar. It is obvious that the slope of the cone in such a machine must be such as to induce the molasses or syrup to flow through the holes and at the same time to permit the sugar to flow along the surface of the basket so that it escapesover the outside of'the cone. If the slope of the cone is made very small, that is, if it is nearly cylindrical in shape, then the centrifugal force has a large United States PatentO 'in accordance with 2,893,562 Patented July 7, 1959 component to cause the escape of the syrup, but the component causing the sugar to flow is too small and thus the sugar tends to accumulate on thecone instead of flowing out over the edge. On the other hand,.if the angle is too wide, then the massecuite flows out rapidly and may carry a large percentage of syrup along with the sugar to the housing which should receive only sugar.

1; is apparent that if the magma is of a type which does not drain rapidly, the angle of the cone must be small so as to give'plenty of opportunity for the syrup to escape and as the syrup is slow to escape then the mass remains relatively fluid and flows readily toward the outer diameter of the'cone. Conversely, if the magma is free-draining, then the conemust have a wide angle to prevent the sugar from becoming. so dry that it will not flow before it reaches the outer. diameter of the cone. For this reason, in such amachine it is desirable that the relation between the force tendingto move the material along the surface of the cone and vthe force tending to bring the syrup through the cone'should be subject to adjustment for each grade of sugar being dried. It is obvious that, as a practical matter, it is impossible to construct a cone which is varied as to its angle without going into so many complications asto make the machine extremely expensive to construct and to maintain.

It is, accordingly, another object of this invention to produce substantially the results which would be obtained from a cone ofvaried'angle and at the same time to avoid expensive and troublesome complications in construction.

The presentinvention is based on the discovery that by positioning blower vanes of suitable design at the outside of the rotating basket in the space between the latter and the conical skirt surrounding it, a vacuum canbe created in this space which increases the forcetending to cause the syrup to flow through the holes in the basket. This force also can actually increase the rapidity of the drying of the sugar and it tends to'hold the sugar against the inside of the cone. Inother words, it has the same efiect as reducing the included angle of the cone. Thus, in accordance with the invention, there is provided a centrifugal of the same general type. as that described above having a cone of a relatively wide angle'but, because it is equipped with the above-mentioned vanes, operates substantially like a cone of a smaller angle.

Moreover, in accordance with the invention, the degree of vacuum in this space between the basket and the skirt is varied by varying the opening in the chute through which the syrup passes after'it has been flung through the apertures in the basket. Thus, if this opening in the chute is nearly cut off by a damper, the vacuum caused by the vanes will be greatly reduced and the cone operates substantially in the manner of a-wide angle cone. However, if the damper is turned with the flow through the chute, then the vacuum acts to accelerate drainage and to hold the sugar against the inside of the cone and then the latter behaves as-if it were .a cone with a smaller angle. Movement of the damper to intermediate positions between fully open and'fully closed ones operates to cause the same effect as progressively changing the included angle of the cone.

The invention will be more readily understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which:

Fig. 1 is an elevation view, with portions in crosssection, of a centrifugal machine of the continuous type the invention together with equipment related thereto; and u Fig. 2 is a cross-section view of one of the housings and the rotating member of the machine of Fig. 1 taken in a plane through line 292 in Fig. 1 and looking in the direction of the arrows.

Referring more specifically to the drawings, Fig. 1 shows, by way of example'for purposes of illustration, a sugar centrifugal;installation. 10. embodying a centrifugal .machine 11" :of the continuous. type in accordance: with the'.invention and certain related pieces of equipment which will be described belowand. which are associated with it in its operation.

The centrifugal machine 11 comprises a first stationary .housingll, a second. stationary housing 13 separated from it, and a member 14 adapted to rotate within and between these housings. The rotating member 14 includes a conical basket 15, the sides of which (or of a lining thereof) are provided with-a multiplicity of apertures '16 jifhrough which syrupflows during the centrifuging process'into thethousing 712, and a conical skirt 17 attached toand adapted'tto rotate with the basket 15. The basket is attached to androtated by a shaft 18 supported within suitable. bearings, such as the member 19, and driven by suitable meanstsuch as the motor 20. Massecuite is appliedto .the'interior of the basket 15 from the source :21, which may be any suitable mixing pan or tank, throughthe? pipe 22. Under the'action of centrifugal force caused by therotation of the basket 15, the syrup is; forcedthroughthe-apertures 16 into the space betweenthe basket 15 arid the'skirt. 17 and thence into the first stationary. housing 12' which is connected at its lower end to a chute. 23which empties into a canal or container 24. The sugar grains left after the syrup has. been driven offflow 'tothe right and finally escape'frorn the conical basket-'15 and are caught by .the second stationary housing 13' which empties through chute 25 into a conveyor 26 which carries the sugar away.

There is a space between the two housings 12 and 13 and this space is open to the atmosphere. As pointed out above, this space is necessary because it is impossible to maintain the air pressures within the housings 12 and 13 always equal and there is a diiference in pressure between these two housings and no space in between, the syrupand sugar will become mixed.'

Since the gradeof sugar. being processed frequently varies from batch to batch, it desirable that the relation between the force tending to move the, material along the surface of the. conical basket 15, and the force tending to. bring the syrup through the apertures 16 should be subject to adjustment for each grade of sugar being dried. Before the presentinvention, it would be necessary to vary the angle of the conical basket 15 in order to attain this desirable result. As already pointed out, such an arrangement would be so expensive as to be completely'impractical in most situations.

This result is, however, simply and relatively inexpensively attained in accordance with the present invention by creating a partial vacuum, the pressure of which can be varied, in the. space between the conical skirt 17 and the conical basket 15. This is accomplished by providing blower'vanes 27 attached to the rotating member 14 (either to the basket 15 or the skirt 17) and suitably shaped to produce a partial vacuum in the region be tween the basket and the If desired, the vanes may be. flat or any other convenient shape. in the drawings, the vanes are. sho nby way'of example attached to the skirt 17. This increases the force tending to cause the sy p to flow hrough the hol s 11 n e basket This force also increases the rapidity of the sugar drying process and tends to hold the sugar against the inside of the conical basket 15, thus having the same effect as reducing the includedangle of the cone. This means that the slope of the cone 16 can be effectively changed (as far as operation is concerned) without actually varying the slope itself.

Cont ol. of hee i ct eqh ng in s qpe. i o ai in accordance with his in euti n, by vary ng he deg e f vacuum in the space between the skirt 17 and the basket 15. One satisfactory way of doing this is to place a damper 28 in the chute 23. When this damper is positioned to cut off the opening in the chute 23, the vacuum caused by the vanes 27 Will not be very high and the basket 15 operates substantially as a wide angle cone. When the damper 28 is in the fully open position (upright in Fig. l the resulting vacuum acts to accelerate the drainage and to hold the sugar grains against the inside of the basket, thus acting as if it were a smaller angle cone. Intermediate positions of the damper 28 (such as that shown in Fig. 1) operate to produce substantially the same effect as cones between wide angle and small angle types. Obviously, the equivalent of a series of cones of progressively difierent slopes is pro duced by the arrangement just described. The pressure between the skirt 17 and the basket 15 can be adjusted to suit the drainage characteristics of the magma being employed,

Obviously, the invention is not limited to the specific structure described above as various changes can be made therein without departing from the spirit or letter of the invention, as indicated in the claims.

What is, claimed is:

1- A s g -dryi g; ce ri a ma e comprising a rotatable basket having amultiplicity of apertures therein, means for continually feeding magma to the interior of said basket, means including a circular skirt surrounding and adapted to rotate with said basket for directing away from the basket liquid from said magma thrown ofi during the sugar drying process, means for producing a pressure lower than atmospheric pressure in the region between said basket and said skirt, and means separate fromsaid last-mentioned means for varying said pressure.

2. A sugar-drying centrifugal machine comprising a rotatable basket having a multiplicity of apertures therein, meansfor continually feeding magma to the interior of said basket, means including a circular skirt surrounding and adapted to rotate with said basket for directing away from the basket liquid from said magma thrown off during the sugar drying process, means for producing a pressure lower than atmospheric pressure in the region between said basket and said skirt, said last-mentioned means including a plurality of vanes positioned to rotate with said basket, and means separate from said pressure producing means for varying said pressure.

3. A sugar-drying centrifugal machine comprising a rotatable basket having a multiplicity of apertures therein, means for continually feeding magma to the interior of said basket, means including a circular skirt surrounding and adapted to rotate with said basket for directing away from the basket liquid from said magma thrown off during the sugar drying process, said lastmentioned means also including a chute, and damper means in saidchute for varying the flow therethrough.

4. A sugar-drying centrifugal machine comprising a rotatable basket having a multiplicity of apertures therein, means for continually feeding magma to the interior of said basket, means including a circular skirt surrounding and adapted to rotate with said basket for directing away from the basket liquid from said magma thrown off duringthe sugar drying process, said lastmentioned means also including a chute, means for producing a pressure lower than atmospheric pressure in the region between said basket and said skirt, and damper means in said chute for varyingsaid pressure.

5. A sugar-drying centrifugal machine comprising a rotatable basket having a multiplicity of apertures therein, means for continually feeding magma to the interior of said basket, means including a circular skirt surrounding and adapted to rotate with said basket for directing away from the basket liquid from said magma thrown off during the sugar drying process, said lastmentioned means also including a chute, means including a plurality of vanes attached to the periphery of said basket and adapted to rotate therewith for producing a pressure lower than atmospheric pressure in the region between said basket and said skirt, and means in said chute for varying said pressure.

6. A sugardrying centrifugal machine comprising a rotatable basket having a multiplicity of apertures therein, means for continually feeding magma to the interior of said basket, means including a circular skirt surrounding and adapted to rotate with said basket for directing away from the basket liquid from said magma thrown off during the sugar drying process, said lastmentioned means also including a chute, means including a plurality of vanes positioned to rotate with said basket for producing a pressure lower than atmospheric pres- References Cited in the file of this patent UNITED STATES PATENTS Dill July 28, 1868 Behr Dec. 8, 1925 Abbott Mar. 28, 1933 Sanchez Oct. 19, 1937 Corwin Apr. 29, 1941 Chappelle Sept. 2, 1941 Bayless Aug. 20, 1946 

